This is attempt #2 of the optimization that replaces the locsBitmap,
without any changes from the original commit attempt. A commit that
follows this one contains the actual fix.
See also...
- commit 621b58dd83 (the 1st attempt)
- commit 49a4ee60ba (the revert)
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The original commit message body from 621b58 was...
NOTE: this is a zap file format change.
The separate "postings locations" roaring Bitmap that encoded whether
a posting has locations info is now replaced by the least significant
bit in the freq varint encoded in the freq-norm chunkedIntCoder.
encode/decodeFreqHasLocs() are added as helper functions.